For reducing power loss and increasing efficiency of a power supply, a high-voltage DC power supply system is provided. By the high-voltage power supply system, the process of converting an AC voltage to a DC voltage is omitted before the electricity is transmitted to the load. Consequently, the operating efficiency is enhanced. Moreover, in views of long-distance power distribution, the high-voltage DC power supply system is more cost-effective and has less power loss than the common AC power supply system. Therefore, the trend of designing a high-voltage DC power supply system is toward low power consumption.
Generally, the high-voltage power supply system comprises a power supply. As known, an isolation transformer is one of the essential components of the power supply. The isolation efficacy of the transformer should be tested according to the safety regulations provided by UL (Underwriter Laboratories Inc., USA), CSA (Canadian Standards Association, Canada) or TUV (Technisher Uberwachungs-Verein, Germany). For example, a hi-pot test is performed to assure safety and reliability of the high-voltage resistant components.
FIG. 1 is a schematic circuit diagram illustrating a conventional power supply. The power supply 1 comprises an isolation transformer 11 for isolating an input terminal 12 from an output terminal 13. In addition, for protecting the user, the output positive terminal 131 or the output negative terminal 132 of the secondary side of the isolation transformer 11 is connected with a ground terminal 14. Consequently, the voltage of the secondary side of the isolation transformer 11 with respect to the ground terminal 14 is Vo or −Vo. In a case that the isolation transformer 11 has a breakdown, the fault current generated by the isolation transformer 11 will be transmitted to the ground terminal 14 to prevent the user from getting an electric shock.
However, since the ground terminal 14 is directly connected with the output positive terminal 131 or the output negative terminal 132, if the magnitude of the output voltage Vo or −Vo is several hundreds of volts (e.g. 400 volts), the demands on the safety regulation and the safety distance of the power supply system 1 become more stringent. Under this circumstance, the number of selective components is reduced, and the fabricating cost is increased. Moreover, since the volume of the common high-voltage resistant component is relatively bulky, the overall volume of the power supply 1 is increased.
Therefore, there is a need of providing a high-voltage power supply module and a power supply system so as to obviate the drawbacks encountered from the prior art.